CN109830749B - Electrolyte and electrochemical device - Google Patents

Electrolyte and electrochemical device Download PDF

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CN109830749B
CN109830749B CN201910073562.1A CN201910073562A CN109830749B CN 109830749 B CN109830749 B CN 109830749B CN 201910073562 A CN201910073562 A CN 201910073562A CN 109830749 B CN109830749 B CN 109830749B
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electrolyte
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carbon atoms
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CN109830749A (en
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张水蓉
栗文强
文倩
唐超
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Ningde Amperex Technology Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C255/00—Carboxylic acid nitriles
    • C07C255/01—Carboxylic acid nitriles having cyano groups bound to acyclic carbon atoms
    • C07C255/02—Carboxylic acid nitriles having cyano groups bound to acyclic carbon atoms of an acyclic and saturated carbon skeleton
    • C07C255/04—Carboxylic acid nitriles having cyano groups bound to acyclic carbon atoms of an acyclic and saturated carbon skeleton containing two cyano groups bound to the carbon skeleton
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C255/00—Carboxylic acid nitriles
    • C07C255/01—Carboxylic acid nitriles having cyano groups bound to acyclic carbon atoms
    • C07C255/02—Carboxylic acid nitriles having cyano groups bound to acyclic carbon atoms of an acyclic and saturated carbon skeleton
    • C07C255/05—Carboxylic acid nitriles having cyano groups bound to acyclic carbon atoms of an acyclic and saturated carbon skeleton containing at least three cyano groups bound to the carbon skeleton
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C255/00—Carboxylic acid nitriles
    • C07C255/01—Carboxylic acid nitriles having cyano groups bound to acyclic carbon atoms
    • C07C255/06—Carboxylic acid nitriles having cyano groups bound to acyclic carbon atoms of an acyclic and unsaturated carbon skeleton
    • C07C255/09—Carboxylic acid nitriles having cyano groups bound to acyclic carbon atoms of an acyclic and unsaturated carbon skeleton containing at least two cyano groups bound to the carbon skeleton
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D239/00—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings
    • C07D239/02—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings
    • C07D239/24—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members
    • C07D239/28—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, directly attached to ring carbon atoms
    • C07D239/46—Two or more oxygen, sulphur or nitrogen atoms
    • C07D239/60—Three or more oxygen or sulfur atoms
    • C07D239/62—Barbituric acids
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D239/00—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings
    • C07D239/02—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings
    • C07D239/24—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members
    • C07D239/28—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, directly attached to ring carbon atoms
    • C07D239/46—Two or more oxygen, sulphur or nitrogen atoms
    • C07D239/60—Three or more oxygen or sulfur atoms
    • C07D239/66—Thiobarbituric acids
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic System
    • C07F7/02—Silicon compounds
    • C07F7/04—Esters of silicic acids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The application provides an electrolyte and an electrochemical device. The electrolyte of the present application includes a carboxylic acid ester, a barbituric acid compound and a nitrile compound. The barbituric acid compound and the nitrile compound with a specific structure are added into the electrolyte containing the carboxylate solvent, so that the rate performance of the electrochemical device can be obviously improved, and the problems of capacity loss, cyclic attenuation and high-temperature flatulence after the electrochemical device is stored at normal temperature are solved.

Description

Electrolyte and electrochemical device
Technical Field
The application relates to the technical field of energy storage, in particular to electrolyte and an electrochemical device comprising the electrolyte.
Background
The lithium ion battery has the advantages of high energy density, long cycle life, no memory effect and the like, and is widely applied to the fields of wearable equipment, smart phones, unmanned aerial vehicles, electric automobiles and the like. Along with the expansion of the application of the lithium ion battery and the development of modern information technology, the requirements of the lithium ion battery on the conventional performance and the rapid charge and discharge performance are also provided, so that how to meet the rapid charge and discharge of the lithium ion battery becomes a problem which needs to be solved urgently in the current industry.
There are many factors that affect the rapid charging and discharging of lithium ion batteries. The electrolyte is used as an important component of the lithium ion battery and has a great influence on the rapid charge and discharge performance of the battery. The rapid charge and discharge capacity of the battery can be effectively improved by improving the electrolyte.
Disclosure of Invention
Embodiments provide an electrolyte including a carboxylic acid ester, a barbituric acid compound, and a nitrile compound, and an electrochemical device including the same. The barbituric acid compound and the nitrile compound with a specific structure are added into the electrolyte containing the carboxylate solvent, so that the rate performance of the electrochemical device can be obviously improved, and the problems of capacity loss, cyclic attenuation and high-temperature flatulence after the electrochemical device is stored at normal temperature are solved.
In one embodiment, the present application provides an electrolyte including a carboxylic acid ester, a barbituric acid compound, and a nitrile compound.
According to an embodiment of the present application, the carboxylic acid ester includes at least one of the compounds represented by formula 1:
Figure BDA0001958030300000011
wherein R is11、R12Each independently selected from C1～12Alkyl or C1～12A haloalkyl group.
According to embodiments herein, the carboxylic acid ester includes one or more of the following compounds: methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate.
According to an embodiment of the present application, the carboxylic acid ester is present in an amount of about 5 wt% to 70 wt%, based on the total weight of the electrolyte.
According to an embodiment of the present application, the barbituric acid compound includes at least one of the compounds represented by formula 2:
Figure BDA0001958030300000021
wherein R is21、R22Each independently selected from hydrogen and C1～12Alkyl radical, C1～12Haloalkyl, C2～12Alkenyl radical, C2～12Haloalkenyl, C6～26Aryl or C6～26A halogenated aryl group;
R23、R24each independently selected from hydrogen, amino, C1～12Alkyl radical, C1～12Haloalkyl, C2～12Alkenyl radical, C2～12Haloalkenyl, C6～26Aryl radical, C6～26Halogenated aryl groups or-NH-R 'where R' is C1～12Alkyl or C1～12A haloalkyl group; and is
X is selected from O or S.
According to embodiments of the application, the barbituric acid compound includes one or more of the following compounds:
Figure BDA0001958030300000022
Figure BDA0001958030300000031
according to an embodiment of the present application, the barbituric acid compound is present in an amount of about 0.01 to 5 wt% based on the total weight of the electrolyte.
According to embodiments of the present application, the nitrile compound includes one or more of the following compounds:
NC-R31-CN formula 3
Figure BDA0001958030300000041
Wherein R is31Is selected from C1～12Alkylene or C1～12An alkyleneoxy group;
R41、R42each independently selected from a bond or C1～12An alkylene group;
R51、R52、R53each independently selected from the group consisting of a bond, C1～12Alkylene or C1～12An alkylene oxide group.
According to embodiments herein, the nitrile compound includes one or more of the following compounds;
Figure BDA0001958030300000042
according to an embodiment of the present application, the nitrile compound is contained in an amount of about 0.5 to 12 wt% based on the total weight of the electrolyte.
According to an embodiment of the present application, the electrolyte further includes a carbonate compound including a silicon functional group.
According to an embodiment of the present application, wherein the silicon functional group-containing carbonate compound includes at least one of the compounds represented by formula 6:
Figure BDA0001958030300000051
wherein R is61And R62Each independently selected from Ra、Si-(Rb)3Or Rc-Si-(Rd)3And R is61And R62At least one of them contains Si;
wherein R iscIs selected from C1～12Alkylene radical, C2～12Alkenylene radical, C6～10Cycloalkylene radical or C6～26An arylene group; and is
Each Ra、Rb、RdIndependently selected from H, C1～12Alkyl radical, C2～12Alkenyl radical, C6～10Cycloalkyl or C6～26Aryl, and R61And R62Each independently substituted or unsubstituted, wherein when substituted, the substituent is halogen.
According to embodiments herein, the silicon-functional carbonate compound includes one or more of the following compounds:
Figure BDA0001958030300000052
according to an embodiment of the present application, the silicon functional group-containing carbonate compound is included in an amount of about 1 wt% to 30 wt%, based on the total weight of the electrolyte.
In another embodiment, the present application provides an electrochemical device comprising a pole piece and an electrolyte, the electrolyte being any of the electrolytes described above.
In another embodiment, the present application provides an electronic device comprising an electrochemical device as described above.
Additional aspects and advantages of embodiments of the present application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of embodiments of the present application.
Detailed Description
Embodiments of the present application will be described in detail below. The embodiments of the present application should not be construed as limiting the present application. The following terms used herein have the meanings indicated below, unless explicitly indicated otherwise.
As used herein, the term "about" is used to describe and illustrate minor variations. When used in conjunction with an event or circumstance, the terms can refer to instances where the event or circumstance occurs precisely as well as instances where the event or circumstance occurs in close proximity. For example, when used in conjunction with numerical values, the term can refer to a range of variation that is less than or equal to ± 10% of the stated numerical value, such as less than or equal to ± 5%, less than or equal to ± 4%, less than or equal to ± 3%, less than or equal to ± 2%, less than or equal to ± 1%, less than or equal to ± 0.5%, less than or equal to ± 0.1%, or less than or equal to ± 0.05%. Additionally, amounts, ratios, and other numerical values are sometimes presented herein in a range format. It is to be understood that such range format is used for convenience and brevity, and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited.
In the detailed description and claims, a list of items connected by the term "one of" may mean any of the listed items. For example, if items a and B are listed, the phrase "one of a and B" means a alone or B alone. In another example, if items A, B and C are listed, the phrase "one of A, B and C" means only a; only B; or only C. Item a may comprise a single element or multiple elements. Item B may comprise a single element or multiple elements. Item C may comprise a single element or multiple elements.
In the detailed description and claims, a list of items connected by the term "at least one of can mean any combination of the listed items. For example, if items a and B are listed, the phrase "at least one of a and B" means a only; only B; or A and B. In another example, if items A, B and C are listed, the phrase "at least one of A, B and C" means a only; or only B; only C; a and B (excluding C); a and C (excluding B); b and C (excluding A); or A, B and C. Item a may comprise a single element or multiple elements. Item B may comprise a single element or multiple elements. Item C may comprise a single element or multiple elements.
As used herein, the term "hydrocarbyl" encompasses alkyl, alkenyl, alkynyl. For example, hydrocarbyl groups are contemplated as straight chain hydrocarbon structures having from 1 to 20 carbon atoms. "hydrocarbyl" is also contemplated to be a branched or cyclic hydrocarbon structure having 3 to 20 carbon atoms. When a hydrocarbyl group having a particular carbon number is specified, all geometric isomers having that carbon number are intended to be encompassed. The hydrocarbyl group herein may also be a hydrocarbyl group of 1 to 15 carbon atoms, a hydrocarbyl group of 1 to 10 carbon atoms, a hydrocarbyl group of 1 to 5 carbon atoms, a hydrocarbyl group of 5 to 20 carbon atoms, a hydrocarbyl group of 5 to 15 carbon atoms, or a hydrocarbyl group of 5 to 10 carbon atoms. In addition, the hydrocarbyl group may be optionally substituted. For example, the hydrocarbyl group may be substituted with halogen, alkyl, aryl or heteroaryl groups including fluorine, chlorine, bromine and iodine.
As used herein, the term "cyclic hydrocarbyl" encompasses cyclic hydrocarbyl. For example, the cycloalkyl group may be a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkyl group having 3 to 15 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, a cycloalkyl group having 5 to 20 carbon atoms, a cycloalkyl group having 5 to 15 carbon atoms or a cycloalkyl group having 5 to 10 carbon atoms. In addition, the cycloalkyl group may be optionally substituted. For example, the cycloalkyl group may be substituted with halogen, alkyl, aryl or heteroaryl groups including fluorine, chlorine, bromine and iodine. As used herein, the term "cycloalkylene" encompasses cyclic cycloalkylene. For example, the cycloalkylene group may be a cycloalkylene group having 3 to 20 carbon atoms, a cycloalkylene group having 3 to 15 carbon atoms, a cycloalkylene group having 3 to 10 carbon atoms, a cycloalkylene group having 3 to 6 carbon atoms, a cycloalkylene group having 5 to 20 carbon atoms, a cycloalkylene group having 5 to 15 carbon atoms or a cycloalkylene group having 5 to 10 carbon atoms. In addition, the cycloalkylene group may be optionally substituted. For example, the cycloalkylene group may be substituted with a halogen, an alkyl group, an aryl group or a heteroaryl group including fluorine, chlorine, bromine and iodine.
As used herein, the term "alkyl" is intended to be a straight chain saturated hydrocarbon structure having from 1 to 20 carbon atoms. "alkyl" is also contemplated to be a branched or cyclic hydrocarbon structure having from 3 to 20 carbon atoms. For example, the alkyl group may be an alkyl group having 1 to 20 carbon atoms, an alkyl group having 1 to 12 carbon atoms, an alkyl group having 1 to 5 carbon atoms, an alkyl group having 5 to 20 carbon atoms, an alkyl group having 5 to 15 carbon atoms or an alkyl group having 5 to 10 carbon atoms. When an alkyl group having a particular carbon number is specified, all geometric isomers having that carbon number are intended to be encompassed; thus, for example, "butyl" is meant to include n-butyl, sec-butyl, isobutyl, tert-butyl, and cyclobutyl; "propyl" includes n-propyl, isopropyl and cyclopropyl. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclobutyl, n-pentyl, isopentyl, neopentyl, cyclopentyl, methylcyclopentyl, ethylcyclopentyl, n-hexyl, isohexyl, cyclohexyl, n-heptyl, octyl, cyclopropyl, cyclobutyl, norbornyl, and the like. In addition, the alkyl group may be optionally substituted.
As used herein, the term "cycloalkyl" encompasses cyclic alkyl groups. The cycloalkyl group can be a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkyl group having 6 to 20 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or a cycloalkyl group having 3 to 6 carbon atoms. For example, cycloalkyl groups can be cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and the like. In addition, cycloalkyl groups may be optionally substituted.
As used herein, the term "alkylene" means a straight or branched chain divalent saturated hydrocarbon group. For example, the alkylene group may be an alkylene group having 1 to 20 carbon atoms, an alkylene group having 1 to 15 carbon atoms, an alkylene group having 1 to 12 carbon atoms, an alkylene group having 1 to 5 carbon atoms, an alkylene group having 5 to 20 carbon atoms, an alkylene group having 5 to 15 carbon atoms or an alkylene group having 5 to 10 carbon atoms. Representative alkylene groups include, for example, methylene, ethane-1, 2-diyl ("ethylene"), propane-1, 2-diyl, propane-1, 3-diyl, butane-1, 4-diyl, pentane-1, 5-diyl, and the like. In addition, the alkylene group may be optionally substituted.
As used herein, the term "alkenyl" refers to a monovalent unsaturated hydrocarbon group that can be straight-chain or branched and has at least one and typically 1,2, or 3 carbon-carbon double bonds. Unless otherwise defined, the alkenyl group generally contains 2 to 20 carbon atoms, and may be, for example, an alkenyl group of 2 to 20 carbon atoms, an alkenyl group of 6 to 20 carbon atoms, an alkenyl group of 2 to 12 carbon atoms, or an alkenyl group of 2 to 6 carbon atoms. Representative alkenyl groups include, by way of example, ethenyl, n-propenyl, isopropenyl, n-but-2-enyl, but-3-enyl, n-hex-3-enyl, and the like. In addition, the alkenyl group may be optionally substituted.
As used herein, the term "alkenylene" encompasses both straight-chain and branched alkenylene groups. When an alkenylene group having a particular carbon number is specified, all geometric isomers having that carbon number are intended to be encompassed. For example, the alkenylene group may be an alkenylene group having 2 to 20 carbon atoms, an alkenylene group having 2 to 15 carbon atoms, an alkenylene group having 2 to 10 carbon atoms, an alkenylene group having 2 to 5 carbon atoms, an alkenylene group having 5 to 20 carbon atoms, an alkenylene group having 5 to 15 carbon atoms, or an alkenylene group having 5 to 10 carbon atoms. Representative alkylene groups include, for example, ethenylene, propenylene, butenylene, and the like. In addition, alkenylene may be optionally substituted. As used herein, the term "aryl" encompasses monocyclic and polycyclic ring systems. Polycyclic rings can have two or more rings in which two carbons are common to two adjoining rings (the rings are "fused"), wherein at least one of the rings is aromatic, e.g., the other rings can be cycloalkyls, cycloalkenyls, aryls, heterocyclics, and/or heteroaryls. For example, the aryl group may be C6～C50Aryl radical, C6～C40Aryl radical, C6～C30Aryl radical, C6～C26Aryl radical, C6～C20Aryl or C6～C10And (4) an aryl group. Representative aryl groups include, for example, phenyl, methylphenyl, propylphenyl, isopropylphenyl, benzyl, and naphthalen-1-yl, naphthalen-2-yl, and the like. In addition, the aryl group may be optionally substituted.
As used herein, the term "arylene" encompasses monocyclic and polycyclic ring systems. Polycyclic rings can have two or more rings in which two carbons are common to two adjoining rings (the rings are "fused"), wherein at least one of the rings is aromatic, and the other rings can be cycloalkyls, cycloalkenyls, aryls, heterocyclics, and/or heteroaryls. For example, the arylene group may be C6～C50Arylene radical, C6～C40Arylene radical, C6～C30Arylene radical, C6～C20Arylene radicals or C6～C10An arylene group. In addition, the arylene group may be optionally substituted.
The term "alkyleneoxy" as used herein refers to a-L-O-group, wherein L is alkylene. For example, the alkyleneoxy group may be an alkyleneoxy group having 1 to 20 carbon atoms, an alkyleneoxy group having 1 to 12 carbon atoms, an alkyleneoxy group having 1 to 5 carbon atoms, an alkyleneoxy group having 5 to 20 carbon atoms, an alkyleneoxy group having 5 to 15 carbon atoms, or an alkyleneoxy group having 5 to 10 carbon atoms. In addition, the alkyleneoxy group may be optionally substituted.
As used herein, the term "nitrile compound" refers to a compound containing a cyano function (-CN).
As used herein, the term "barbituric acid compound" encompasses barbituric acid and derivatives thereof.
As used herein, the term "halogen" encompasses F, Cl, Br, I.
As used herein, the term "bond" encompasses a single bond, a carbon-carbon double bond, or a carbon-carbon triple bond.
When the above substituents are substituted, the substituents may be selected from the group consisting of: halogen, alkyl, cycloalkyl, alkenyl, aryl.
As used herein, the content of each component in the electrolyte is obtained based on the total weight of the electrolyte.
First, electrolyte
An embodiment of the present application provides an electrolyte including a carboxylic acid ester, a barbituric acid compound, and a nitrile compound.
In some embodiments, the carboxylic acid ester is selected from at least one of the compounds represented by formula 1:
Figure BDA0001958030300000091
wherein R is11、R12Each independently selected from C1～20Alkyl radical, C1～12Alkyl radical, C1～6Alkyl radical, C1～20Haloalkyl, C1～12Haloalkyl or C1～6A haloalkyl group.
In some embodiments, the carboxylic acid ester is selected from one or more of the following compounds: methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate.
In some embodiments, the carboxylic acid ester is present in an amount of about 5 wt% to about 70 wt%, based on the total weight of the electrolyte. In some embodiments, the carboxylic acid ester is present in an amount of about 10 wt% to about 60 wt%. In some embodiments, the carboxylic acid ester is present in an amount of about 20 wt% to about 50 wt%. In some embodiments, the carboxylic acid ester is present in an amount of about 30 wt% to about 40 wt%. If the content of the carboxylic ester is about 5 to 70 wt%, the performance of reducing impedance and improving the rate of the battery is obviously improved, and irreversible side reactions are reduced.
In some embodiments, the barbituric acid compound is selected from at least one of the compounds represented by formula 2:
Figure BDA0001958030300000092
wherein R is21、R22Each independently selected from hydrogen and C1～20Alkyl radical, C1～12Alkyl radical, C1～6Alkyl radical, C1～20Haloalkyl, C1～12Haloalkyl, C1～6Haloalkyl, C2～20Alkenyl radical, C2～12Alkenyl radical, C2～6Alkenyl radical, C2～20Haloalkenyl, C2～12Haloalkenyl, C2～6Haloalkenyl, C6～50Aryl radical, C6～26Aryl radical, C6～12Aryl radical, C6～50Halogenated aryl, C6～26Halogenated aryl radicals or C6～12A halogenated aryl group;
R23、R24each independently selected from hydrogen, amino, C1～20Alkyl radical, C1～12Alkyl radical, C1～6Alkyl radical, C1～20Haloalkyl, C1～12Haloalkyl, C1～6Haloalkyl, C2～20Alkenyl radical, C2～12Alkenyl radical, C2～6Alkenyl radical, C2～20Haloalkenyl, C2～12Haloalkenyl, C2～6Haloalkenyl, C6～50Aryl radical, C6～26Aryl radical, C6～12Aryl radical, C6～50Halogenated aryl, C6～26Halogenated aryl radicals or C6～12Halogenated aryl, or-NH-R ', wherein R' is C1～20Alkyl radical, C1～12Alkyl radical, C1～6Alkyl radical, C1～20Haloalkyl, C1～12Haloalkyl or C1～6A haloalkyl group; and is
X is selected from O or S.
In some embodiments, the barbituric acid compound is selected from one or more of the following compounds:
Figure BDA0001958030300000101
Figure BDA0001958030300000111
in some embodiments, the barbituric acid compound is present in an amount of about 0.01 to 5 wt% based on the total weight of the electrolyte. In some embodiments, the barbituric acid compound is present in an amount of about 0.01% to 4% by weight. In some embodiments, the barbituric acid compound is present in an amount of about 0.01% to 3% by weight. In some embodiments, the barbituric acid compound is present in an amount of about 0.01% to 2% by weight. In some embodiments, the barbituric acid compound is present in an amount of about 0.05 wt% to 5 wt%. In some embodiments, the barbituric acid compound is present in an amount of about 1 wt% to about 3 wt%. When the content of the barbituric acid compound is about 0.01 wt% to 5 wt%, a complete and effective Cathode Electrolyte Interface (CEI) film can be formed on the surface of the positive electrode, so that side reactions caused by electron transfer between the electrolyte and the electrode can be effectively prevented.
In some embodiments, the nitrile compound is selected from one or more of the following compounds:
NC-R31-CN formula 3
Figure BDA0001958030300000112
Wherein R is31Is selected from C1～20Alkylene radical, C1～12Alkylene radical, C1～6Alkylene radical, C1～20Alkyleneoxy group, C1～12Alkyleneoxy or C1～6An alkyleneoxy group;
R41、R42each independently selected from the group consisting of a bond, C1～20Alkylene radical, C1～12Alkylene or C1～6An alkylene group;
R51、R52、R53each independently selected from the group consisting of a bond, C1～20Alkylene radical, C1～12Alkylene radical, C1～6Alkylene radical, C1～20Alkyleneoxy group, C1～12Alkyleneoxy or C1～6An alkylene oxide group.
In some embodiments, the nitrile compound is selected from one or more of the following compounds;
Figure BDA0001958030300000121
in some embodiments, the nitrile compound is present in an amount of about 0.5 to 12 wt% based on the total weight of the electrolyte. In some embodiments, the nitrile compound is present in an amount of about 0.5% to 10% by weight. In some embodiments, the nitrile compound is present in an amount of about 0.5% to 5% by weight. In some embodiments, the nitrile compound is present in an amount of about 2% to 5% by weight. In some embodiments, the nitrile compound is present in an amount of about 2 wt% to about 10 wt%. In some embodiments, the nitrile compound is present in an amount of about 3% to about 10% by weight. When the content of the nitrile compound in the electrolyte is about 0.5 wt% -12 wt%, the nitrile compound has obvious isolation effect on the surface of the anode and easily-oxidized components in the electrolyte, and obviously improves the cycle performance and the high-temperature storage performance of the lithium ion battery.
In some embodiments, the electrolyte may further include a carbonate compound including a silicon functional group. The carbonic ester compound containing silicon functional groups, the carboxylic ester, the barbituric acid compound and the nitrile compound act together to enable the electrolyte to have excellent chemical stability, thermal stability and oxidation resistance and low surface tension, a stable protective film can be formed on the surface of an electrode, the capacity loss of the lithium ion battery after storage at normal temperature is improved, and the decomposition heat of the electrolyte on the surface of the electrode in the overcharge process is improved, so that the overcharge performance of the lithium ion battery is improved.
In some embodiments, the silicon functional group-containing carbonate compound is selected from at least one of the compounds represented by formula 6:
Figure BDA0001958030300000122
wherein R is61And R62Each independently selected from Ra、Si-(Rb)3Or Rc-Si-(Rd)3And R is61And R62At least one of them contains Si;
wherein R iscIs selected from C1～12Alkylene radical, C2～12Alkenylene radical, C6～10Cycloalkylene radical or C6～26An arylene group; and is
Wherein each Ra、Rb、RdIndependently selected from H, C1～20Alkyl radical, C1～12Alkyl radical, C1～6Alkyl radical, C2～20Alkenyl radical, C2～12Alkenyl radical, C2～6Alkenyl radical, C6～20Cycloalkyl radical, C6～10Cycloalkyl radical, C6～50Aryl radical, C6～26Aryl radical, C6～12Aryl, and R61And R62Each independently substituted or unsubstituted, wherein when substituted, the substituent is halogen.
In some embodiments, the silicon-functional carbonate compound is selected from one or more of the following compounds:
Figure BDA0001958030300000131
in some embodiments, the silicon functional group-containing carbonate compound is present in an amount of about 1 wt% to 30 wt%, based on the total weight of the electrolyte. In some embodiments, the silicon functional group-containing carbonate compound is present in an amount of about 1 wt% to about 20 wt%. In some embodiments, the silicon functional group-containing carbonate compound is present in an amount of about 1 wt% to about 15 wt%. In some embodiments, the silicon functional group-containing carbonate compound is present in an amount of about 1 wt% to about 10 wt%. In some embodiments, the silicon functional group-containing carbonate compound is present in an amount of about 5 wt% to 20 wt%. In some embodiments, the silicon functional group-containing carbonate compound is present in an amount of about 10 wt% to 20 wt%.
In some embodiments, the electrolyte includes a lithium salt selected from one or more of inorganic lithium salts and organic lithium salts. In some embodiments, the lithium salt is selected from one or more of the following lithium salts: lithium hexafluorophosphate (LiPF)6) Lithium difluorophosphate (LiPO)2F2) Lithium tetrafluoroborate (LiBF)4) Lithium hexafluoroarsenate, lithium perchlorate, lithium bis (fluorosulfonylimide) (LiFSI), lithium bis (trifluoromethanesulfonylimide) (LiTFSI), LiB (C) bis (oxalato-borate)2O4)2(LiBOB) and LiBF Difluoro oxalato boronic acid2(C2O4)(LiDFOB)。
In some embodiments, the concentration of the lithium salt is about 0.5M to 1.5M. In some embodiments, the concentration of the lithium salt is about 0.8M to 1.3M. In some embodiments, the concentration of the lithium salt is about 0.5M to 1.2M.
In some embodiments, the electrolyte further includes a carbonate-based compound. The carbonate may be any kind of carbonate as long as it can be used as the nonaqueous electrolyte organic solvent.
In some embodiments, the carbonate is a cyclic carbonate or a chain carbonate.
In some embodiments, the cyclic carbonate is selected from one or more of the following carbonates: ethylene carbonate, propylene carbonate, butylene carbonate, gamma-butyrolactone, pentylene carbonate, fluoroethylene carbonate and halogenated derivatives thereof. The above cyclic carbonates may be used alone or in combination of two or more.
In some embodiments, the chain carbonates are selected from one or more of the following carbonates: dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate and halogenated derivatives thereof. The above chain carbonates may be used alone or in combination of two or more.
In some embodiments, the electrolyte may further contain other additives known in the art to improve the performance of the battery, such as Solid Electrolyte Interface (SEI) film forming additives, flame retardant additives, anti-overcharge additives, conductive additives, and the like.
Two, electrochemical device
The electrochemical device of the present application includes any device in which electrochemical reactions occur, and specific examples thereof include all kinds of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors. In particular, the electrochemical device is a lithium secondary battery including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery. In some embodiments, an electrochemical device according to the present application is an electrochemical device including a positive electrode having a positive electrode active material capable of occluding and releasing metal ions and a negative electrode having a negative electrode active material capable of occluding and releasing metal ions, and is characterized by including any of the above-described electrolytic solutions according to the present application.
Electrolyte solution
The electrolyte used in the electrochemical device of the present application is any of the electrolytes described above in the present application. In addition, the electrolyte used in the electrochemical device of the present application may further include other electrolytes within a range not departing from the gist of the present application.
Negative electrode
The material, composition, and manufacturing method of the negative electrode used in the electrochemical device of the present application may include any of the techniques disclosed in the prior art. In some embodiments, the negative electrode is the negative electrode described in U.S. patent application US9812739B, which is incorporated by reference in its entirety.
In some embodiments, the negative electrode includes a current collector and a negative active material layer on the current collector. The negative active material includes a material that reversibly intercalates/deintercalates lithium ions. In some embodiments, the material that reversibly intercalates/deintercalates lithium ions comprises a carbon material. In some embodiments, the carbon material may be any carbon-based negative active material commonly used in lithium ion rechargeable batteries. In some embodiments, carbon materials include, but are not limited to: crystalline carbon, amorphous carbon, or mixtures thereof. The crystalline carbon may be amorphous, flake, platelet, spherical or fibrous natural or artificial graphite. The amorphous carbon may be soft carbon, hard carbon, mesophase pitch carbide, calcined coke, or the like.
In some embodiments, the negative active material layer includes a negative active material. In some embodiments, the negative active material includes, but is not limited to: lithium metal, structured lithium metal, natural graphite, artificial graphite, mesophase micro carbon spheres (MCMB), hard carbon, soft carbon, silicon-carbon composites, Li-Sn alloys, Li-Sn-O alloys, Sn, SnO2Spinel-structured lithiated TiO2-Li4Ti5O12A Li-Al alloy, or any combination thereof.
When the anode includes a silicon carbon compound, the ratio of silicon: the carbon is about 1:10 to 10:1, and the silicon carbon compound has a median particle diameter D50 of about 0.1 to 100 um. When the negative electrode includes an alloy material, the negative electrode active material layer can be formed by a method such as an evaporation method, a sputtering method, or a plating method. When the anode includes lithium metal, the anode active material layer is formed, for example, with a conductive skeleton having a spherical strand shape and metal particles dispersed in the conductive skeleton. In some embodiments, the spherical-stranded conductive skeleton may have a porosity of about 5% to about 85%. In some embodiments, a protective layer may also be disposed on the lithium metal anode active material layer.
In some embodiments, the negative active material layer may include a binder, and optionally a conductive material. The binder improves the binding of the negative active material particles to each other and the binding of the negative active material to the current collector. In some embodiments, the adhesive includes, but is not limited to: polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene 1, 1-difluoroethylene, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, and the like.
In some embodiments, the conductive material includes, but is not limited to: a carbon-based material, a metal-based material, a conductive polymer, or a mixture thereof. In some embodiments, the carbon-based material is selected from natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, or any combination thereof. In some embodiments, the metal-based material is selected from the group consisting of metal powder, metal fiber, copper, nickel, aluminum, silver. In some embodiments, the conductive polymer is a polyphenylene derivative.
In some embodiments, the current collector includes, but is not limited to: copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymeric substrates coated with a conductive metal, and any combination thereof.
The negative electrode may be prepared by a preparation method well known in the art. For example, the negative electrode can be obtained by: the active material, the conductive material, and the binder are mixed in a solvent to prepare an active material composition, and the active material composition is coated on a current collector. In some embodiments, the solvent may include water, and the like, but is not limited thereto.
Positive electrode
The material of the positive electrode used in the electrochemical device of the present application may be prepared using materials, configurations, and manufacturing methods well known in the art. In some embodiments, the positive electrode of the present application can be prepared using the techniques described in US9812739B, which is incorporated by reference in its entirety.
In some embodiments, the positive electrode includes a current collector and a positive active material layer on the current collector. The positive electrode active material includes at least one lithiated intercalation compound that reversibly intercalates and deintercalates lithium ions. In some embodiments, the positive electrode active material includes a composite oxide. In some embodiments, the composite oxide contains lithium and at least one element selected from cobalt, manganese, and nickel.
In some embodiments, the positive active material is selected from lithium cobaltate (LiCoO)2) Lithium Nickel Cobalt Manganese (NCM) ternary material, lithium iron phosphate (LiFePO)4) Lithium manganate (LiMn)2O4) Or any combination thereof.
In some embodiments, the positive electrode active material may have a coating layer on a surface thereof, or may be mixed with another compound having a coating layer. The coating may comprise at least one coating element compound selected from the group consisting of an oxide of the coating element, a hydroxide of the coating element, an oxyhydroxide of the coating element, an oxycarbonate of the coating element and an oxycarbonate of the coating element. The compounds used for the coating may be amorphous or crystalline.
In some embodiments, the coating elements contained in the coating may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or any combination thereof. The coating layer may be applied by any method as long as the method does not adversely affect the properties of the positive electrode active material. For example, the method may include any coating method known to the art, such as spraying, dipping, and the like.
The positive active material layer further includes a binder, and optionally a conductive material. The binder improves the binding of the positive electrode active material particles to each other, and also improves the binding of the positive electrode active material to the current collector.
In some embodiments, the adhesive includes, but is not limited to: polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene 1, 1-difluoroethylene, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy, nylon, and the like.
In some embodiments, the conductive material includes, but is not limited to: carbon-based materials, metal-based materials, conductive polymers, and mixtures thereof. In some embodiments, the carbon-based material is selected from natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, or any combination thereof. In some embodiments, the metal-based material is selected from the group consisting of metal powder, metal fiber, copper, nickel, aluminum, silver. In some embodiments, the conductive polymer is a polyphenylene derivative.
In some embodiments, the current collector may be aluminum, but is not limited thereto.
The positive electrode may be prepared by a preparation method well known in the art. For example, the positive electrode can be obtained by: the active material, the conductive material, and the binder are mixed in a solvent to prepare an active material composition, and the active material composition is coated on a current collector. In some embodiments, the solvent may include, but is not limited to, N-methylpyrrolidone, and the like.
In some embodiments, the positive electrode is made by forming a positive electrode material on a current collector using a positive electrode active material layer including a lithium transition metal-based compound powder and a binder.
In some embodiments, the positive electrode active material layer may be generally fabricated by: the positive electrode material and a binder (a conductive material, a thickener, and the like, which are used as needed) are dry-mixed to form a sheet, and the obtained sheet is pressure-bonded to a positive electrode current collector, or these materials are dissolved or dispersed in a liquid medium to form a slurry, and the slurry is applied to a positive electrode current collector and dried. In some embodiments, the material of the positive electrode active material layer includes any material known in the art.
Diaphragm
In some embodiments, the electrochemical device of the present application is provided with a separator between the positive electrode and the negative electrode to prevent short circuit. The material and shape of the separator used in the electrochemical device of the present application are not particularly limited, and may be any of the techniques disclosed in the prior art. In some embodiments, the separator includes a polymer or inorganic substance or the like formed of a material stable to the electrolyte of the present application.
For example, the separator may include a substrate layer and a surface treatment layer. The substrate layer is a non-woven fabric, a film or a composite film with a porous structure, and the material of the substrate layer is at least one selected from polyethylene, polypropylene, polyethylene terephthalate and polyimide. Specifically, a polypropylene porous film, a polyethylene porous film, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite film can be used.
At least one surface of the substrate layer is provided with a surface treatment layer, and the surface treatment layer can be a polymer layer or an inorganic layer, or a layer formed by mixing a polymer and an inorganic substance.
The inorganic layer comprises inorganic particles and a binder, wherein the inorganic particles are selected from one or more of aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium oxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide and barium sulfate. The binder is selected from one or a combination of more of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene. The polymer layer comprises a polymer, and the material of the polymer comprises at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or poly (vinylidene fluoride-hexafluoropropylene).
Third, application
The electrolyte solution provided by the embodiment of the application can be used for improving the rate performance, the normal-temperature storage capacity retention rate and the cycle and high-temperature storage performance of a battery, and is suitable for being used in electronic equipment comprising an electrochemical device.
The use of the electrochemical device of the present application is not particularly limited, and the electrochemical device can be used for various known uses. Such as a notebook computer, a pen-input computer, a mobile computer, an electronic book player, a cellular phone, a portable facsimile machine, a portable copier, a portable printer, a headphone, a video recorder, a liquid crystal television, a portable cleaner, a portable CD player, a mini disc, a transceiver, an electronic organizer, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, an automobile, a motorcycle, a power-assisted bicycle, a lighting fixture, a toy, a game machine, a clock, an electric tool, a flashlight, a camera, a large-sized battery for home use, or a lithium ion capacitor.
Examples
The present application will be described in more detail below with reference to examples and comparative examples, but the present application is not limited to these examples as long as the gist thereof is not deviated.
Preparation of lithium ion battery
(1) Preparation of positive plate
The positive electrode active material lithium cobaltate (LiCoO)2) Conductive agent (Super)
Figure BDA0001958030300000181
The conductive carbon) and polyvinylidene fluoride are mixed according to the weight ratio of 97:1.4:1.6, N-methyl pyrrolidone (NMP) is added, and the mixture is stirred under the action of a vacuum stirrer until the system is uniform, so as to obtain anode slurry, wherein the solid content of the anode slurry is 72 wt%; uniformly coating the positive electrode slurry on a positive electrode current collector aluminum foil; drying the aluminum foil at 85 ℃, then carrying out cold pressing, cutting into pieces, slitting, and drying for 4 hours at 85 ℃ under a vacuum condition to obtain the positive plate.
(2) Preparation of negative plate
Mixing the negative active material artificial graphite and conductive agent (Super)
Figure BDA0001958030300000182
The conductive carbon), the sodium carboxymethylcellulose (CMC) and the Styrene Butadiene Rubber (SBR) as the binder are mixed according to the weight ratio of 96.4:1.5:0.5:1.6, deionized water is added, and the mixture is stirred in vacuumObtaining negative pole slurry under the action of a mixer, wherein the solid content of the negative pole slurry is 54 wt%; uniformly coating the negative electrode slurry on a copper foil of a negative electrode current collector; and drying the copper foil at 85 ℃, then carrying out cold pressing, cutting and slitting, and drying for 12h at 120 ℃ under a vacuum condition to obtain the negative plate.
(3) Preparation of the electrolyte
Mixing solvents (such as Ethylene Carbonate (EC), Propylene Carbonate (PC), diethyl carbonate (DEC), Ethyl Acetate (EA), Methyl Propionate (MP), and Ethyl Propionate (EP)) at a certain weight ratio in a dry argon atmosphere glove box, adding additives (such as barbituric acid compound, nitrile compound, and carbonate compound containing silicon functional group), dissolving and stirring thoroughly, adding lithium salt LiPF6And mixing uniformly to obtain the electrolyte. Wherein, LiPF6The concentration of (2) was 1.05 mol/L. The content of each substance in the electrolyte is calculated based on the total weight of the electrolyte.
(4) Preparation of the separator
A Polyethylene (PE) barrier film of 12 μm thickness was used.
(5) Preparation of lithium ion battery
And sequentially stacking the positive plate, the isolating film and the negative plate to enable the isolating film to be positioned between the positive plate and the negative plate to play an isolating role, then winding and welding a tab, placing the tab in an outer packaging foil aluminum plastic film, injecting the prepared electrolyte into a dried naked battery cell, performing vacuum packaging, standing, formation (charging to 3.3V at a constant current of 0.02C, and then charging to 3.6V at a constant current of 0.1C), shaping, capacity testing and other procedures to obtain the soft package lithium ion battery (with the thickness of 3.3mm, the width of 39mm and the length of 96 mm).
A. The electrolytes of examples 1 to 30 and comparative examples 1 to 14 and the lithium ion batteries were prepared according to the above-described methods.
TABLE 1
Figure BDA0001958030300000191
Figure BDA0001958030300000201
Wherein "-" means that the substance was not added.
The lithium ion batteries of examples 1 to 30 and comparative examples 1 to 14 were tested for high temperature cycle performance, high temperature storage performance, and 2C discharge efficiency, and the test procedures were as follows:
(1) lithium ion battery high-rate discharge performance test
The lithium ion batteries obtained in comparative examples 1 to 14 and examples 1 to 30 were charged at a constant current/constant voltage of 0.5C to 4.4V at 25 ℃, left for 10min, discharged at a constant current of 0.5C to a cut-off voltage of 3.0V, and the discharge capacity was recorded. Charging to 4.4V at 25 deg.C under constant current/constant voltage of 0.5C, standing for 10min, discharging to cut-off voltage of 3.0V under constant current of 2C, and recording discharge capacity. The ratio of the discharge capacity to the 0.5C capacity at 25 ℃ is the 2C discharge efficiency. The lithium ion battery 2C discharge performance test data for comparative examples 1-14 and examples 1-30 are shown in Table 2.
(2) Capacity conservation rate test of lithium ion battery after normal temperature storage
And (3) placing the lithium ion battery in a constant temperature box at 25 ℃, and standing for 30 minutes to keep the temperature of the lithium ion battery constant. Charging the lithium ion battery reaching the constant temperature to the voltage of 4.4V by using a 1C constant current, then charging to the current of 0.05C by using a 4.4V constant voltage, and then discharging to the voltage of 3.0V by using a 1C constant current, wherein the capacity is initial capacity; charging to 3.85V at a constant current of 1C, then charging to 0.05C (about 50% State of Charge (SOC)) at a constant voltage of 3.85V, storing at 25 ℃ for 6 months, discharging to 3.0V at a constant current of 1C, then charging to 4.4V at a constant current of 1C, then charging to 0.05C at a constant voltage of 4.4V, then discharging to 3.0V at a constant current of 1C, and finally discharging the capacity to be the reversible capacity after storage;
capacity retention (%) of the lithium ion battery after normal temperature storage is equal to reversible capacity/initial capacity after storage × 100%
(3) Cycle performance testing of lithium ion batteries
And (3) placing the lithium ion battery in a constant temperature box at 45 ℃, and standing for 30 minutes to keep the temperature of the lithium ion battery constant. The lithium ion battery reaching a constant temperature was charged at a constant current of 1C to a voltage of 4.4V, then charged at a constant voltage of 4.4V to a current of 0.05C, and then discharged at a constant current of 1C to a voltage of 3.0V, which is a charge-discharge cycle. Thus, the capacity retention rates after the battery was cycled 300 times and 500 times were calculated, respectively. The 45 ℃ cycle test data for the lithium ion batteries of comparative examples 1-14 and examples 1-30 are shown in Table 2.
The capacity retention (%) after N cycles of the lithium ion battery was equal to the discharge capacity at the N-th cycle/the first discharge capacity × 100%.
(4) High temperature storage performance testing of lithium ion batteries
Charging the lithium ion batteries obtained in comparative examples 1-14 and examples 1-30 to 4.4V at a constant current of 0.5C at room temperature, then charging the batteries at a constant voltage until the current is 0.05C, and testing the thickness of the lithium ion batteries and marking the thickness as h 0; and then putting the lithium ion battery into a constant temperature box at 60 ℃, preserving the heat for 30 days, testing the thickness of the lithium ion battery every 10 days, and recording the thickness as hn, wherein n is the number of days for high-temperature storage of the lithium ion battery. The 60 ℃ storage test data for the lithium ion batteries of comparative examples 1-14 and examples 1-30 are shown in Table 2.
The lithium ion battery has a thickness expansion ratio (%) of (hn-h0)/h0 × 100% after n days of high temperature storage.
TABLE 2
Figure BDA0001958030300000221
Figure BDA0001958030300000231
It can be seen from the test results of comparative examples 1 to 7 and examples 1 to 26 that the barbituric acid compound and the nitrile compound having a specific structure are simultaneously added to the electrolyte containing carboxylic ester, thereby significantly improving the rate performance of the lithium ion battery, and simultaneously improving the irreversible capacity loss after normal temperature storage, the cycle performance and the high temperature storage performance.
From the test results of comparative examples 2, 3 and 7 and examples 2 and 10 to 23, it can be seen that when the electrolyte contains both 1 wt% of the barbituric acid compound and 0.5 to 12 wt% of the specific nitrile compound, the capacity loss and the high-temperature storage performance after the normal-temperature storage of the battery can be improved. As can be seen from the test results of comparative examples 2, 3 and 7 and examples 2 to 9, when the electrolyte contains both of 2 wt% of the nitrile compound and 0.01 wt% to 5 wt% of the barbituric acid compound, the capacity loss after the storage at normal temperature of the battery, as well as the high-temperature storage performance and the cycle performance, can be improved. The test results show that when the electrolyte contains the carboxylic ester, the barbituric acid compound and the nitrile compound with a specific structure, the high-rate performance of the battery can be effectively improved, and the problems of irreversible capacity loss, cyclic attenuation, high-temperature storage flatulence and the like after the lithium ion battery is stored at normal temperature are solved.
B. To the electrolyte solution of example 2 was added a carbonate compound having a silicon functional group to prepare electrolyte solutions of examples 31 to 40.
The batteries of examples 2 and 31 to 40 were tested for capacity retention and overcharge performance after storage at ordinary temperature. The test results are shown in Table 2.
The overcharge performance test process comprises the following steps: the battery is discharged to 2.8V at 25 ℃ at 0.5C, is charged to 5V at 2C constant current, and is charged for 3h at constant voltage, and the battery does not burn and explode, which represents that the battery core passes the test.
TABLE 2
Figure BDA0001958030300000241
Wherein "-" means that the substance was not added.
From the test results of examples 31 to 40 and example 2, it can be seen that the addition of the carbonate compound containing a silicon functional group to the electrolyte containing the barbituric acid compound and the nitrile compound can improve the capacity retention rate of the battery after storage at room temperature, and also greatly improve the overcharge performance of the battery cell.
The above description is only for the purpose of illustrating the present invention and is not intended to limit the present invention in any way, and the present invention is not limited to the above description, but rather should be construed as being limited to the scope of the present invention.
Reference throughout this specification to "some embodiments," "one embodiment," "another example," "an example," "a specific example," or "some examples" means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. Thus, throughout the specification, descriptions appear, for example: "in some embodiments," "in an embodiment," "in one embodiment," "in another example," "in one example," "in a particular example," or "by example," which do not necessarily refer to the same embodiment or example in this application. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.
Although illustrative embodiments have been illustrated and described, it will be appreciated by those skilled in the art that the above embodiments are not to be construed as limiting the application and that changes, substitutions and alterations can be made to the embodiments without departing from the spirit, principles and scope of the application.

Claims (14)

1. An electrolyte comprising a carboxylic acid ester, a barbituric acid compound and a nitrile compound, wherein the nitrile compound comprises one or both of the following compounds:
Figure FDA0003007572150000011
Figure FDA0003007572150000012
and is
The content of the barbituric acid compound is 4 to 5 wt% based on the total weight of the electrolyte.
2. The electrolyte of claim 1, wherein the carboxylic acid ester comprises at least one of the compounds represented by formula 1:
Figure FDA0003007572150000013
wherein R is11、R12Each independently selected from C1～12Alkyl or C1～12A haloalkyl group.
3. The electrolyte of claim 1, wherein the carboxylic acid ester comprises one or more of the following compounds:
methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate.
4. The electrolyte of claim 1, wherein the carboxylic acid ester is present in an amount of 5 to 70 wt% based on the total weight of the electrolyte.
5. The electrolyte of claim 1, wherein the barbituric acid compound includes at least one of the compounds represented by formula 2:
Figure FDA0003007572150000014
wherein R is21、R22Each independently selected from hydrogen and C1～12Alkyl radical, C1～12Haloalkyl, C2～12Alkenyl radical, C2～12Haloalkenyl, C6～26Aryl or C6～26A halogenated aryl group;
R23、R24each independently selected from hydrogen, amino, C1～12Alkyl radical, C1～12Haloalkyl, C2～12Alkenyl radical, C2～12Haloalkenyl, C6～26Aryl radical, C6～26Halogenated aryl groups or-NH-R 'where R' is C1～12Alkyl or C1～12A haloalkyl group; and is
X is selected from O or S.
6. The electrolyte of claim 1, wherein the barbituric acid compound comprises one or more of the following compounds:
Figure FDA0003007572150000021
Figure FDA0003007572150000031
7. the electrolyte of claim 1, wherein the nitrile compound further comprises one or more of the following compounds:
NC-R31-CN formula 3
Figure FDA0003007572150000032
Wherein R is31Is selected from C1～12Alkylene or C1～12An alkyleneoxy group;
R41、R42each independently selected from a bond or C1～12An alkylene group.
8. The electrolyte of claim 1, wherein the nitrile compound further comprises one or more of the following compounds;
Figure FDA0003007572150000033
9. the electrolyte according to claim 1, wherein the content of the nitrile compound is 0.5 to 12% by weight, based on the total weight of the electrolyte.
10. The electrolyte of claim 1, further comprising a silicon functional group-containing carbonate compound, wherein the silicon functional group-containing carbonate compound comprises at least one of the compounds represented by formula 6:
Figure FDA0003007572150000041
wherein R is61And R62Each independently selected from Ra、Si-(Rb)3Or Rc-Si-(Rd)3And R is61And R62At least one of them contains Si;
wherein R iscIs selected from C1～12Alkylene radical, C2～12Alkenylene radical, C6～10Cycloalkylene radical or C6～26An arylene group; and is
Wherein each Ra、Rb、RdIndependently selected from H, C1～12Alkyl radical, C2～12Alkenyl radical, C6～10Cycloalkyl or C6～26Aryl, and R61And R62Each independently substituted or unsubstituted, wherein when substituted, the substituent is halogen.
11. The electrolyte of claim 10, wherein the silicon-functional-group-containing carbonate compound comprises one or more of the following compounds:
Figure FDA0003007572150000042
12. the electrolyte of claim 10, wherein the silicon functional group-containing carbonate compound is present in an amount of 1 wt% to 30 wt%, based on the total weight of the electrolyte.
13. An electrochemical device, wherein the electrochemical device comprises the electrolyte of any one of claims 1-12.
14. An electronic device comprising the electrochemical device of claim 13.
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